Powwerflex Modbus

[b_carlton 61]

There is data available starting at Modbus address 8448 on a Powerflex 4 (at least) drive. The officially supported information is: 8448 - Logic Status Data (bits) 8449 - Drive Error Code More information I have found continues this: 8450 - Commanded Frequency 8451 - Output Frequency 8452 - Output Current 8453 - DC Bus Voltage 8454 - Output Voltage My question is - does anyone have information for addresses past these?

[Ken Roach 194]

Where did you get those address descriptions ? They correspond with the sequence of parameter descriptions in the 232-SCM serial converter user manual. But they look like the Display parameter "dxxx" group, but with the parameters swapped in pairs. I'm looking at the Display Parameter group in the PowerFlex 4 Quick Start (22A-QS001). The actual PowerFlex 4 User Manual (22A-UM001) says that for Modbus code 03 (read Holding Register) the register address = the Parameter address. The offset of 2100 (hex) = 8448 (decimal) might be for an Assembly or other Parameter Group.

[b_carlton 61]

I found the first two plus the 8451 in the manual (only the first two were in earlier manuals) The larger list of parameters was in an Excel spreadsheet I found online. I'll have to track it down. I see the listing in the SCM manual. Whether it is getting at these in the same way that Modbus gets them I don't know. But the additional items in the list aren't of interest to me so I probably won't persue it. Here's a PDF of the spreadsheet my information came from. And now I found my original source: http://www.ab.com/support/abdrives/powerflex4/appnotes.html PowerFlex 4 ModBus-RTU Addressing.pdf Edited 1 Mar 2011 by b_carlton

[Ken Roach 194]

Thanks for posting that ! That little note on the bottom of the PDF document is key, saying that you can read a block of data from the "2100 hex" offset address, while the ordinary "1-offset" parameter access will respond only to single parameter reads. This supports the hypothesis that there's an Assembly of display parameters that is readable as a higher address range than the ordinary parameters. This is similar to the way multi-drive mode works.

[slcman 9]

I did few project with modbus comms. Ken your right, paramter can be read/write by using parameter number. Sometime you'll need to add 1 to modbus adress so 8449 error code will be 8450. If you didn't take care of this offset, logic status data 8448 will be read as error code 8449 (8448 + 1). Don't write parameter on all plc scan, EEprom failure will occur. Another thing, for read more than 1 parameter, I change the size in Element value (see picture).